1. Field of the Invention
The present invention relates to image pickup control techniques suitable for controlling, from an external apparatus, an image pickup apparatus such as a video camera for electronically performing an image pickup operation.
2. Related Background Art
Peripheral apparatuses of a personal computer (hereinafter abbreviated as PC), such as a hard disk drive and a printer, are connected to PC via a small computer general interface typically a SCSI (Small Computer System Interface) of a digital interface (hereinafter described as a digital I/F). Data communication between PC and peripheral apparatuses is performed via the digital I/F.
Recently, cameras for electronically performing an image pickup operation, such as digital cameras and digital video cameras, are positively used as peripheral apparatuses for inputting an image to PC. Specifically, a still image or moving image taken with a digital camera or video camera as well as associated sounds is entered to PC and stored in a hard disk, or edited and thereafter printed out by a color printer. Techniques in this field have been developed greatly and the number of users is increasing rapidly. With such techniques, when image data entered from a camera into PC is output to a printer or hard disk, data communication is performed via SCSI or the like. In this case, since image data having a large data amount is transferred, a digital I/F is required to have a high data transfer rate and be suitable for general use.
FIG. 33 shows a conventional system configuration of a digital camera and a printer both connected to a PC. In FIG. 33, reference numeral 31 represents a digital camera, reference numeral 32 represents a PC, and reference numeral 33 represents a printer. Reference numeral 34 represents a memory serving as a storage unit of the digital camera 31, reference numeral 35 represents a decoding circuit for image data, reference numeral 36 represents an image processing unit, reference numeral 37 represents a D/A converter, reference numeral 38 represents an EVF functioning as a display unit, and reference numeral 39 represents a digital I/O unit for the digital camera 31. Reference numeral 40 represents a digital I/O unit for PC 32 for the connection to the digital camera 31, reference numeral 41 represents an operation unit such as a keyboard and a mouse, reference numeral 42 represents a decoding circuit for image data, reference numeral 43 represents a display, reference numeral 44 represents a hard disk drive, reference numeral 45 represents a memory such as a RAM, reference numeral 46 represents a MPU as a computation unit, reference numeral 47 represents a PCI bus, and reference numeral 48 represents a SCSI interface (board) as a digital I/F. Reference numeral 49 represents a SCSI interface of the printer 33 connected to PC 32 via a SCSI cable, reference numeral 50 represents a memory, reference numeral 61 represents a printer head, reference numeral 52 represents a printer controller as a printer control unit, and reference numeral 53 represents a driver.
The following processes are executed in order to enter an image taken with the digital camera into PC 32 and output the image from PC 32 to the printer 33. Namely, in the digital camera, image data stored in the memory 34 and read therefrom is decoded by the decoding circuit 35, processed for image data display by the image processing circuit 36, and displayed on EVF 38 via the D/A converter 37. In order to output image data to PC 32, the image data is supplied to the digital I/O unit 40 of PC 32 via the digital I/O unit 39.
In PC 32, the PCI bus 47 is used as an internal transfer bus. The image data input from the digital I/O unit 40 is either stored in a hard disk of the hard disk drive 44, or displayed on the display 43 after it is decoded by the decoding circuit 42, stored in the memory 46 and converted into analog signals in the display 43. When image data is edited by PC 32, necessary data is input via the operation unit 41. The control of the whole system of PC 32 is performed by MPU 46.
When an image is to be printed out, the image data is transferred from PC 32 and via the SCSI interface unit 48 and SCSI cable to the SCSI interface unit 49 of the printer 33, and converted into print image data in the memory 50. The printer controller 52 controls the printer head 61 and driver 53 to print out the print image data in the memory 50.
As above, each peripheral apparatus is connected to PC which functions as a host, and image data picked up with a camera is printed out via PC. However, SCSI is associated with several problems including a low transfer data rate, a thick parallel communications cable, restrictions on the type of a connectable peripheral apparatus and on the connection method, and a necessity of I/F connectors same in number as the number of connection destinations.
Most of general home use PCes and digital apparatuses have connectors for connection to SCSI and cables on the back panel thereof. The size of such a connector is large and a work of inserting and removing the connector is cumbersome. Even a mobile or portable apparatuses which are not used as a mount-type, such as a digital camera and a video camera, is required to be connected to the connector on the back panel of PC and a user feels very cumbersome.
Digital data communications have been heretofore typically mutual communications between PC and its peripheral apparatus, and conventional communications systems are not so much inconvenient. However, it is expected that the number of types of apparatuses handling with digital data increases, and that not only PC peripheral apparatuses, but also other digital apparatuses such as digital video apparatuses and digital recording medium reproducing apparatuses can be connected to a network with the advent of improved I/F to realize network communications. Although network communications are very convenient, communications with a large data amount are performed often between some apparatuses. In such a case, the network traffics become congested and communications between other apparatuses in the network may be affected adversely, if a conventional communication method is used.
Digital I/F for general use (such as high performance serial bus IEEE 1394-1995 (The Institute of Electrical and Electronics Engineers)) has been proposed which is applicable to communications not only between PC and its peripheral apparatuses but also between digital apparatuses of various types and can solve problems of conventional digital I/F as much as possible. By using such digital I/F for general use, PCes, their peripheral apparatuses such as printers, digital cameras, digital VTRs with built-in camera, and the like are connected together to configure a network and realize data communications between these apparatuses.
Main characteristics of IEEE 1394 reside in that, as will be later detailed, its cable is relatively thin and rich in flexibility and its connector is very small as compared to a SCSI cable because of high speed serial communications, and that data having a large capacity such as image data can be transferred together with apparatus-control data at high speed. With communications using IEEE 1394 I/F, even a portable apparatus which is not usually used as a mount-type, such as a digital camera and a video camera, can be connected easily with a considerably reduced conventional cumbersome work, and image data ca be transferred to PC smoothly.
As above, IEEE 1394 I/F has various advantages which overcome cumbersome works associated with a conventional data communications system. Data having a large capacity, particularly image data, can be transferred together with apparatus control data at high speed. It is therefore possible, for example, for PC to perform a remote real time control of an image pickup apparatus typically a video camera in accordance with image data transferred from the image pickup apparatus. There is therefore a high possibility to realize the conventional issue of remotely and reliably controlling an image pickup from another apparatus.